Add in a constructable structure similar to a wardrobe but functionally different. The wardrobifier allows users to change the look of their items based on skins that they've unlocked for their account. Skins can be unlocked via actions in-game as well as purchased from a cash shop. Skins applied only apply to the character who used the wardrobifier, so removing an item or trading it away will return it to its original skin. As skins are account bound, any character on that account will have access to them.
A similar idea can be applied to buildings and other constructable objects. Applying the skin before placing the structure allows us to make buildings look different even if they function the same.
Allow us to measure how oblong our ego is based on the fancy skins and colors we can use to turn our characters and villages into an eyesore. We will all happily throw money at you to put in extra graphical work for this.